Adaptive Multilevel Modeling of Land-Atmosphere Interactions

Abstract

Adaptive multilevel methods allow full coupling of atmospheric and land surface hydrological models by preserving consistency between the large-scale (atmospheric) and the regional (land) components. The methodology was investigated for three case studies involving the coupling of models with different levels of complexity and different spatial resolutions. The first case study consisted of coupling two simple models. One model provided the potential and the other the rotational components of atmospheric wind fields, which were used to drive a 3D orographic precipitation model used to investigate the long-term precipitation for the Olympic Mountains in Washington State. In the second case study, intermittent coupling (every 4 hours) of three versions of the orographic precipitation model operating at 40-m, 60-m, and 80-km resolution, respectively, was established to replicate the precipitation patterns of specifically chosen storms as they evolved across the central Sierra Nevada region. The third case study consisted of coupling the orographic precipitation model (40-km resolution) to a 1D model describing mass and energy balance conditions at the land surface for the northern and central Sierra Nevada region. Numerical coupling of the precipitation and the land surface models was implemented on a 2D finite-element mesh with 10-km resolution. One contribution of this study was the long-term simulation of the intra-annual dynamics of the hydrological cycle in a mountainous environment.